While the FDA limits caffeine in soft drinks, it does not
regulate energy drinks. In turn, energy drinks push the caffeine
envelope in an effort to gain marketshare. Many drinks contain
eight times as much caffeine as a 12-ounce can of Coke. And that
can pay off for athletes.

A study conducted by the Journal of the International Society of
Sports Nutrition proved caffeine enhances athletic performance –
reaction time and endurance, in particular.

Yet caffeine's benefits come with dangerous consequences. One
high school athlete downed two energy drinks before a football
game – not uncommon in his locker room – and suffered a seizure
that nearly lead to his death.

The substance's wide-ranging effects on various people make it
especially difficult for regulators to control. While some
advocate the drug's benefits, others want it banned in sports, or
at least limited for minors.